Vacuum switch for alternating currents



March 11, 1930. H. EGG

VACUUM SWITCH FOR ALTERNATING CURRENTS Filed Feb. 25, 1928 Patented Mar.11,1930

UNITED STATES PATENT OFFICE HABTMANN EGG, OF ZURICH, SWITZERLAND,ASSIGNOR TO THE FIRM MASCHINEN- FABRIK OERLIKON, OF OEBLIKON, NEARZURICH, SWITZERLAND, A CORPORATION OF SWITZERLAND VACUUH SWITCH FORALTERNATING- CURRENTS Application filed February.25, 1928, Serial No.

This invention relates to a vacuum switch for alternating currents.

In high frequency practice it is known to switch alternating currents bymeans of vacuum valves, in such a manner, that for each vacuum valves.

semi-cycle one vacuum valve is employed, in which case by virtue of thestarting-up and continuous excitation of the valves, the alternatingcurrent is switched on and maintained, whilst the interruption of thealternating current is effected by interrupting the excitation.

If this arrangement is employed for switching heavy currents, thedisadvantage is encountered that in the vacuum valves in consequence ofthe arc voltage, a continuous loss is encountered and must be led off inthe form of heat. The vacuum valves must consequently be dimensioned fora correspondingly high continuous load. These 'd sadvan tages can beovercome by short-circuiting the vacuum valves under normal conditionsof operation by means of mechanical switches and initiating thestarting-up and excitation of said valves immediately before theswitching operation is commenced and interrupting same after themechanical switch has opened. This measure has the result that thevacuum valves have to conduct the current only during the period duringwhich the mechanical switch is open, that is to say during a fewsemi-cycles, so that no appreciable loss of energy and heating takesplace. It is consequently possible to employ vacuum valves which aredimensioned for relatively small permanent currents, since such valvescan be loaded without difliculty for a short period with a multiple oftheir permanent load current.

The mechanical switch is for its own part only dimensioned for aswitching off load which corresponds to the arc voltage of the Accordinto the present invention, the initiation o the starting-up andexcitation of the vacuum valves as well as the interruption thereof atthe termination of the movement of the mechanical switch, is effected ina pos itive manner in dependence on the positionon the mechanicalswitch, in such a manner that 257,030, and in Switzerland February 25,1927.

the interruption of the current by this latter cannot take place beforethe starting-up and excitation of the vacuum valves has been initiatedand completed, and that this latter is interrupted only after thecurrent has been interrupted by the mechanical switch to such an extentthat arcing across the latter is no longer possible.

In order more clearly to understand the invention, reference is made tothe accompanying drawing which illustrates diagrammatically and by wayof example one embodiment of an arrangement according to the invention.

In said drawing 1 and 2 indicate respectively the input and output leadsof the alternating current which is to be interrupted. 3 and 4 indicatethe vacuum valves which are constituted as mercury vapour valves. 5 and6 are the anodes, 7 and 8 the mercury-cathodes of the respective valves,the permeability of which is indicated by the direction of the arrows. 9and 10 indicate electromagnetically actuated starting-up devices whichafter completion of the starting-up simultaneously act as continuousexciters by means of the direct current supplied by the batteries 11 and12. The resistances 14 and 15 serve to limit the starting-up andexcitation current. 16 is the fixed and 17 the movable contact of themechanical switch. These contacts 16 and 17 are in parallel with thevalves 3 and 4. 18 is an auxiliary contact which moves upwardly with thecontact 17 on switching OE and in so doing glides on the immovablecontact rail 19 until movable contact rails 29 and 30, which arepositively mechanically connected with the movable contact 17 butinsulated from each other and from said contact 17, have interconnectedstationary cont-acts 21, 22 and 23, 24 and thus effected the starting-upand excitation of the valves. The valves are thus completely energizedprior to the opening of the contacts 18 and 19.

The flow of current now takes place through the valves, and theauxiliary contact 16 that arcing is definitely out of the question, todisconnect said circuit contacts on recesthe contact rails 29 and 30interrupt the exsion of saidswitch contacts beyond arcing citation,whereupon the current is extinrange.

guished in the valves. On switching-on, the valves first come intooperation. 25 indicates a small resistance which serves to take the loadofi the auxiliary contact 18 when. the switch is closed and to divertthe arcing voltage into the vacuum valves.

Both valves with their current leads mutually insulated in a suitablemanner may be combined into a single vacuum chamber.

Moreover a plurality of vacuum valves may said switches closing saidstarting-up and ex-.

citation circuits prior to opening of said mechanical switching meansand opening said excitation circuits after opening beyond arcing rangeof said mechanical switching means.

2. In a vacuum switch for alternating currents, vacuum valves permeableto opposite semi-cycles of said current connected in parallel,starting-up and excitation circuits of said valves contacts in saidcircuits, contact rails mova le across said circuit contacts, a switchcontact connected to one side of said valves, and a movable switchcontact connected to the opposite side of said valves and mechanicallyconnected to said switch rails, said contact rails and movable switchcontact moving in unison to interconnect said circuit contacts prior tointerruption of direct electric interconnection of said switch contactsand to disconnect said circuit contacts on recession of said switchcontacts beyond arcing range.

3. In a vacuum switch for alternating currents, vacuum valves permeableto opposite semi-cycles of said current connected in parallel,starting-up and excitation circuits of said valves, contacts in saidcircuits, contact rails movable across said circuit contacts, a switchcontact connected to one'side of said valves, a contact rail, aresistance interconnecting said switch contact and said contact rail, amovable switch contact connected to the opposite side of said valves andmechanically connected to said movable switch rails, and an auxiliarycontact connected to said movable switch contact and contacting withsaid resistance-connected contact rail, said first mentioned contactrails, said movable switch contact and said auxiliary contact -moving inunison to interconnect said circuit contacts prior to said auxiliarycontact leaving said-resistance-connected contact rail and In testimonywhereof, I aflix my signature.

HARTMANN EGG.

